CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-3activerecordruby-on-rails-3.2
MKK
MKK

Reputation: 2753

How can I sort by few columns?

I wrote scope like this

/models/code.rb

scope :recent, lambda { |n = 10| includes(:user).where('users.deleted_at' => nil).order("users.last_active_at DESC").limit(n) }

However, there are the records that have the same users.last_active_at sometimes.

So I tried adding created_at DESC to it like below.

scope :recent, lambda { |n = 10| includes(:user).where('users.deleted_at' => nil).order("users.last_active_at DESC, created_at DESC").limit(n) }

But I get this error. What's wrong with my code? Indeed there is a column called created_at in codes table.

Error (Mysql2::Error: Unknown column 'created_at' in 'order clause'

Upvotes: 0

Views: 45

Answers (1)

Christian Rolle
Christian Rolle

Reputation: 1684

Since includes decides whether or not the users are joined to the codes table in one SQL query or 2 separate queries are generated (for performance reasons) you should ensure, that you are referring the users table and its created_at column:

    scope :recent, lambda { |n = 10| includes(:user).
      where('users.deleted_at' => nil).
      order("users.last_active_at DESC, users.created_at DESC").
      limit(n) }

Also think about merging scopes for responsibility reasons as you can read about here: Merge your ActiveRecord scopes

Upvotes: 1

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